#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
	int a[10] = {0};
	double b = 0;
	for (int i = 0; i < 10; i++)
	{
		scanf("%d ", &a[i]);
	}
	for (int j = 0; j < 10; j++)
	{
		 b += a[j];
	}
	double c = b / 10.0;
	printf("%lf\n", c);
	return 0;
}